A container terminal provided at a land of a harbor for loading or unloading of a container is a base for marine transportation by ships and land transportation by trucks, trains or the like, and berth facilities for ships (container ships), container loading and unloading facilities, container storage facilities and so on are organically constructed therein to facilitate smooth container distribution. Also, the container terminal is organically connected to a land transportation network including loads and railways.
In order to distribute containers without congestion at a harbor, a system for efficiently managing the entire container terminal is required, and also it is important to procure sufficient relevant facilities such as berth facilities for ships (container ships), container landing and carrying facilities, container storage facilities and so on.
In relation to landing/lifting of containers, a gantry crane installed at a container terminal or the like is a crane for a harbor, which has a door or bridge shape, and is used for stacking containers carried by trailers or loading the stacked containers on trailers.
As such a gantry crane, there is proposed a rail mounted gantry crane which moves on rails installed at a container terminal or the like, depending on its running method. The rail mounted gantry crane has an advantage in that a power on the land is directly connected and used through a cable reel or the like, but also has a disadvantage in that it has a bad degree of mobility freedom since it runs only on rails.
To overcome the above drawback, a tired gantry crane for generating power by operating a diesel engine in the crane itself and using the generated power has been recently proposed. The tired gantry crane may freely move to various places on roads, instead of rails, and thus ensures a high degree of mobility freedom in comparison to the rail mounted gantry crane.
Due to expensive oil price and environment pollution, a power source on the land is used as a main power by transmitting power through a cable reel or a booth bar, like the rail mounted gantry crane. The power is supplied from a power source installed at a container terminal in advance through a cable reel.
However, the method for supplying power required for driving a tired gantry crane by using a cable reel as described above is just allowed at a region where a cable reel is connected, and thus this greatly limits the degree of mobility freedom of the tired gantry crane.
In addition, in addition to tired gantry crane using a cable reel, there is also known a tired gantry crane using a hybrid method, which is driven using an electric battery (electric energy) and an internal combustion engine (fossil energy) in order not to damage the degree of mobility freedom. However, the hybrid method demands a great early-stage investment in comparison to a gantry crane using a cable reel, which uses only electric energy, and also there still remains a serious problem in environments since it uses a diesel fuel.
FIG. 1a is a diagram schematically showing an appearance of a container terminal installed at a tired gantry crane. In the container terminal as shown in FIG. 1a, if a cargo ship 1000 having a container cargo reaches a harbor, containers are primarily landed by a container crane 2000 installed at the harbor, and the landed containers are moved by a gantry crane 3000 to be stacked and stored at each workspace A to D or loaded on and carried by yard chassis (not shown) or yard tractors (not shown). On the contrary, containers carried by yard chassis or yard tractors may also be shipped on the cargo ship 1000).
In the container terminal, the tired gantry crane 3000 generally works at a predetermined workspace A to D and moves along a predetermined path. The inventors of the present disclosure have designed the invention from the understanding that the working performance of the tired gantry crane 3000 can be improved even though a battery-rechargeable power source is used instead of a cable reel, as long as the tired gantry crane 3000 can obtain necessary energy at each workspace.
Generally, a gantry crane needs to move to a certain location in order to unload a container carried by a trailer or loading a stored container on a trailer. For this, the gantry crane has a travelling mechanism. The tired gantry crane moves through a manual manipulation of a driver along a moving lane marked on the ground (movement in lanes) and unloads a container.
In order to apply unmanned operation thereto, a line mark is generally used in the existing technique as a gantry crane running method. In this running method, a line mark is marked along a running path of a crane, and a camera for photographing the line mark in real time is installed. In addition, a location of the line mark is continuously found by using image information acquired through the camera, and a motor is controlled using a program logic controller so that the crane is located within a predetermined range from the center of the line mark, thereby guiding stable straight running of the crane.
However, this existing crane running method has problems as follows.
First, the crane may collide. In the existing technique, since the camera is fixedly focused on the line mark while the crane is running, a crane running direction, namely, a front view, should be monitored substantially depending on the sight of a driver. For this reason, if a driver does not detect an obstacle present in the crane running direction, the crane may collide with the obstacle, and this accident may cause material damages and, on occasions, damage of human life.
Second, works are seriously limited by external environmental (weather) conditions. In the existing technique, when it rains, particularly when it is snowy, the line mark may not be easily recognized, and thus it is very difficult to drive the crane by detecting the line mark through a camera. For example, if snow is piled up on the ground, it is substantially impossible to detect the line mark through a camera, and also when ice is formed on the line mark, it is substantially impossible to acquire image information through the camera. For this reason, in these cases, it is impossible to drive a crane, and a snow-removing work is required for driving the crane, which may delay the work.
Third, efficiency and productivity for optimized landing are deteriorated. In the existing technique, a transport vehicle such as a trailer for carrying a container should be stopped just due to the experience of a driver of the transport vehicle, and thus the transport vehicle should be adjusted by forward or backward movement when unloading the container, which deteriorates work efficiency and productivity of the crane.
Meanwhile, in a vertically-arranged harbor structure frequently used in Europe or the like, in relation to landing/lifting of a container, the container has a short transport distance, and thus three works for loading a container on a yard tractor by a crane and storing a newly carried container by the yard tractor crane may be operated just by a straddle carrier, which lifts a container and moves by itself.
A gantry crane installed at a container terminal or the like is a crane for a harbor, which has a door or bridge shape, and is used for stacking a container carried by a straddle carrier and placed on the ground or moving a stacked container to a location where the container may be loaded on a straddle carrier.
FIG. 1b is a diagram schematically showing a vertically-arranged container terminal. In the container terminal as shown in FIG. 1b, if a cargo ship having a container reaches a harbor, containers are primarily unloaded and placed on the ground by a container crane installed at the harbor, and a straddle carrier picks the container placed on the ground, moves the container to an open storage yard and places the container on the open storage yard. Then, the yard crane picks the container placed on the ground again and stacks on the open storage yard.
On the contrary, a container carried by a straddle carrier is shipped on a cargo ship in a reverse order to the above.
The straddle carrier is equipment capable of picking a container and moving a short distance in a container terminal, and its greatest advantage is to reduce a standby time of an existing vertically-arranged harbor, during which a crane should wait until a yard trailer comes or until a yard trailer loads a container.
As shown in FIG. 1b, the straddle carrier just moves from a rear location of a crane of FIG. 1b, which unloads a container, to an entrance of a container loading region due to its special use in the container yard. From the fact that a straddle carrier moves only within a predetermined loading area or along a predetermined path, the inventors of the present disclosure have designed the invention from the understanding that if energy for operating a vehicle can be obtained in each workspace, all problems of a straddle carrier of hybrid method which uses a mixture of fossil fuel and electric fuel and a straddle carrier of a battery method which operates with a large-capacity battery can be solved together.
In addition, for an unmanned operation of a straddle carrier, in an existing technique, a guideline is generally formed using a paint or the like along a path along which the straddle carrier should move so that the straddle carrier may run by recognizing the guideline with a camera, or a transponder or the like is generally buried in the ground so that the straddle carrier may run by recognizing a location of the sensor. However, if a guideline is formed on the road, the guideline may not be recognized in a snowy day, which disturbs the unmanned operation. In addition, if the guideline is erased as time goes, the guideline should be repaired, which requires maintenance costs. From this, the inventors have designed an unmanned operation using a laser scanner such as a global positioning system (GPS).